Motor fuels and processes for making same



Pl'll l0, 1945. l.. A. CLARKE MOTOR FUELS AND PROCESSES FOR MAKING SAME Filed Feb. 4. 1942 NDEODJ... ZmUQmnI llllll WZSPDDOW- lll 4 butylene mixture, is employed Patented pr. 10, 1945 oFFlcE MOTOR FUELS PROCESSES FOR MAKING SAME Louis s. cnr-ke, Fishkill, N. r., assigner to 'rile Texas` Company, New York, N. Y., a corporation of Delaware Application February 4, 1942, serial No. 429,412 12 claims. ici. aai-se) My invention relates to an improved process :for the alkylation of isobutane. and for the pro. duction of superior anti-knock motor fuels. More specifically, my invention relates to the utilization of mixtures of normal and isobutylenes for the alkylation of isobutane, and to the production of improved aviation type motor fuels.

The alkylation of lsobutane by means of mixed normal and isobutylenes, using mineral acid catalysts, produces alkylates having desirable anti-'- lmoclr characteristics for .'irdinary automotive and aviation uses. In accordance with the present invention, superior alkylates are produced which have unusually high anti-knock properties and lead susceptlbilities desirable for the produc-v tion of highly' leaded aviation type "super fuels.

y The lprocess of my invention is illustrated in the single heure oi' the accompanying drawing showing the process diagrammatically with the aid of legends.

I have found that improved alkylates, suitable for use in aviation fuels of highmwer output. can be obtained from mixtures of normal and isobutylenes by separate alkylations of isobutanc by means or the normal and isobutylene components oi'- such mixtures', using different cata lysts for the two alkylations. In my preferred process, an isobutylene alkylating agent derived from the butylene mixture, is employed in conjunction with a the alkylation ol' isobutane; and aY normal butylene alkylatlng agent, derived from the same in conjunction with a sulfuric acid catalyst for the alkylation of isobutape.

octane values and high lead susceptibilities.

` These. blends may be heavily leaded to produce high power output-aviation fuels having excellent performance in supercharged engines. Y In the process of the present invention. prefer- `ably at least a maior portion of the isobutylene is separated from the butylene-ccntaining mixture' in the `form of an isobutylene alkylating agent of the class consisting of monomeric iso- 45 consisting of n-butylcneo and n-butylcne addition products such ssecconduy butyl alcohol 55 and secondary butyl acid sulfate, is employed for I agent suitable for use in the hydrogen fluoride hydrogen iluorlde catalyst for 3 The resulting alkylates may be blended to produce motor fuels of high clear the alkylation of isobutane in the presence of a sulfuric acid catalyst.

Any of the butylene-containing gas mixtures I commercially available in refineries may be employed in the present procesabut the advantages of this process arebest realized in the utilization of mixtures in which neither isobutylene nor n-butylenes'4 predominate to any great extent. Suitable mixtures contain substantial amounts of isobutylene and either or both butylene-l and buty1ene-2. Commercially available mixtures usually also contain isobutane, which is utilized as one oi the reactants in the present process..

and may also contain normal butane and lesser amounts of other gaseous hydrocarbons. The

preferred mixtures contain only hydrocarbons with four carbon atoms, and in Vsuch mixtures,

.normal butane is preferably maintained at as low a concentration as is economically practical.

The separation of lsobutylene from the butylene-ccntedning mixtures may be eected by any of the'lrnown methods. This operation, however, is preferably carried out in a manner such as to -yield directly an isobutylene alkylating alkylation, and to yield a normal butylene alkylating agent suitable for use in the sulfuric acid alkylation f Belectiveabsorption of isobutylene in dilute sulfuric acid, e. g.; 60 to '70 per centv strength, constitutes a desirable procedure for separating this component from the gas mixtures. Isobutylene may be regenerated fromv the resulting solution by suitable methods, or the solution may be neutralized and then distilled to yield tertiary butyl alcohol. which may also serve as an alkylating agent in the hydrogen uoride allryla.- tion. In the latter case, water of reaction will be formed during the alkylation, and must be taken into consideration, in view of its diluting action on the catalyst.

Vammisione alkylaung 5 A desirable modication of the above procedure is to heat; the sulfuric acid solution to form isobutylene polymers, for example, inaccordance With'the procedure 0f U. S. Patent 2,258,368. The

di-isobutylene and tri-isobutylene which may be obtained by 'this procedure areVlv satisfactory alkylating agents for the hydrogen fluoride alkylation, but I generally prefer to form largely the di-isobutylene for this` purpose.` l Alternatively, the di-isobutylene may be formed directly, in a singley step, by contacting the butylene mixture with sulfuric acid under conditions to eilcct selective polymerization of the 30' minutes. l

strength of at least 95j pe' cent is preferably isobutylene. accompanying drawing, which represents a ow diagram of a preferred method for carrying out the present invention.

The butylene-containing gas mixture may also be treated Withihydrogen fluoride to form ,tertiary` butyl fluoride for` use as an alkylating agent in the hydrogen fluoride alkylation step of the process. Selective hydrouorination of isobutylene is desirable for this purpose, .but it is also possible to form both tertiary butyl fluoride and secondary butyl fluoride, and to decompose 'the latter to regenerate normal butylenes for use in the sulfuric acid alkylation. The hydroiluorination may be eiected in the vapor phase in the presence of catalysts such as fiuorides of zinc, manganese, cobalt, .iron or aluminum. Conversely, the hydrofluorination may be effected in the liquid phase in the absence of catalysts, for A example, in accordance with the process Grosse and Linn (J. Org. Chem., 3, 26).

In the above processes, or any equivalent processes for the separation of isobutylene, the isobutylene alkylatin'g agent produced may suitably be eithermonomeric or polymeric. On the other hand, for ,the production of high quality alkylates in the sulfuric acid alkylation step, .I prefer to employ only monomeric n-butylene alkylating agents, i. e., alkylating agents of the class consisting of butylene-l, butylene-2, and. n-butylene addition products, such as secondary butyl alcohol and secondary butyl acid sulfate.

w 'I'he alkylation of isobutane by means of the isobutylene alkylating'agentis veiiected in the presence of a. hydrogen fluoride catalyst in accordance with the procedure of' my co-pending application, Serial Number 429,471, filed February 4, 1942. For the productionof high quality 'alkylates in this step of the process, a high ratio of isobutane to isobutylene alkylating agent should be employed in the reaction mixture.v This ratio should not be less than' 4:1, and

and to employ a space velocity below 5 and pref-v This modication is shown in' the recycle to effect an internal isobutane to olefin f ratio of at least 100:1 and preferably about 150:1,

erably below 1, calculated as volumes of ,total hydrocarbon feed, including external recycle, per volume of acid catalyst per hour. It is to be understood, however, that these conditions are not limiting, but are merely illustrative of known reaction conditions which are suitable for this step of the process.

My invention may be further illustrated by the following specic example:

A gas mixture of the following approximate composition: y

' Mol per cent Propane 4.6 Propylene 0.9 Isobutane 22.0 Isobutylene 10.0 N-butylenesl 10.7 N-butane 50.0 C5 and higher 1.8

is, contacted with 65 per cent sulfuric acid te absorb approximately 90 per cent of the isobutylene content, and to yield a residual gas mixture of approximately the following composition:

Mol per cen Propane 5.0 Propylene 1.0 Isobutane 24.2 Isobutylene i 1.1 N-butylenesl 11.7 N-butane 55.0 C5 and higher 2.0

Isobutane is added to this residual gas mixture in suflicient quantity to produce an isobutane to. olei'ln ratio of 22.3 and the resulting mixture is continuously introduced into a reactionvessel containing 100 per cent sulfuric acid in a quantity sumcient to produce an acid to hydrocarbon shouldpreferably be at least 5:1. Although the isobutane to olen ratio is the most important factor in this step of the process, it is also desir able to employ optimum reaction temperatures, and other reaction conditions, a's described in lmy co-pending application. ,When using the preferred reaction conditions ibr the hydrogen fiuoiride alkylation, alkylates may be secured having CFRM octane numbers as high as 97 or even higher, 4and having high lead susceptibility and excellent perfomance in superchargedengines when leaded to the extent of 3 .c.c. or more of 1 tetraethyl lead per gallon.-

The residual gas mixture containing the .f n-butylene alkylating -agent may be employed to alkylate, isobutane in. the presence of a sulfuric acid catalyst, using any of the known vconditions "for sulfuric acid alkylation. Here again,.opti' mum conditions are desirable for the production of highest quality alkylates. As examples of suitable .reaction conditions, there may be men-l tioned temperatures of 'to '60 F.,isobutane to olefin ratios of at least 5.5'21'in. the feed lmixratio in the reaction mixture of approximately' 1.7:1 by volume. The reaction mixture' is agitated and maintained at approximately 60 F.

and the rate of feed is maintained suflicient to produce a contact time of 20 minutes. The resulting emulsion is drawn oif from the vessel at ture, -acid strength of 94 to 100 per cent, an acid to hydrocarbon ratio of at least 1:1 by volume and preferably about 1.-'I:1,A and -a contact time of at least 20 minutes and preferably at least In continuous operation, an acid maintained in thereaction zone 'by the use of.

make-up acid of 98 to 100 per cent concentra-` tion. For continuous operation,'it is .also desirable to employ emulsion recycle'and isobutane .a rate corresponding to the rate of hydrocarbon feed andv catalyst recycle, is allowed to separate and the catalyst phase is continuously returned tothe vreaction vessel. 'Ihe hydrocarbon phase is'then distilled to yield a debutanized alkylate of`311 F. E. P.

The sulfuric acid solution isobutylene absorption described above is heated proximately 5 minutes to effect polymerization of the isobutylene, primarily to di-isobutylene.

VThe resulting v(li-isobutylene is recovered byl distillation of the separated hydrocarbon layer, and is employed for the alkylation of isobutane in the presence of substantially anhydrous hydrogen fluoride as the catalyst. For .this purpose,

,the isobutane and hydrogen uoride are charged into a reaction vessel equipped with a. rotary agitator, and di-isobutylene is added to theagitated mixture over a. period of 60 minutes, while maintaining a temperature of '10 F. The isobutane, di-isobutylene, and hydrogen fluoride are employed in a mol ratio of 5:1:5 respectively. Following the introduction of the di-isobutylene, agitation is continued for an additional 30 minutes, after which the emulsion is allowed to separate, and the hydrocarbon phase is distilled to recover debutanized alkylate.

resulting from the .insCFR ternative or from the group consisting of have been obtained tents of at least 85 having total' octane' con- CFRM octane numbers of 95-97; and n-butylene alkylates'have been secured-hav- M octane numbers ates,l when blended in the motor fuels having clear octane values of S45-96.5. On the other hand, alkylations of mixed gases containing isobutylene and n-butylenes in the ratio oi'the olen gas mixture of the above example have yielded alkylates having clear octane numbers of only'93 to 94.

The blended alkylates, produced as 4described above, alsohave superior lead susceptibilities, and may be leaded as heavily at 6-.0 c.c. ofV tetraethyl lead per gal. to produce fuels of extremely high maximum power output. Very satisfactory aviation type miotor ,fuels can be prepared from such blended alkylates by incorporating a more volatile blending fractionsuch as isopentane or 2,3-dimethylbutane, and leading the resultin of seas. 'These any1- proportions produced from -the original b utylene mixture, result in A per cent by volume, contents of 2,2,4-trimethylpentane of at least 55 per cent by volume, and

Zbon' selected from the CFRM octane otat 3 lIn representativealkylations-under the condiwith a space velocity below recovering a de-Y tions described above, di-isobutylene alkylates butanized alkylate therefrom having a clear least 94, blending the said debutanized alkylates to produce a mixture having high lead susceptibility, adding theretoa minor proportion oi' a more volatile hydrocargroup consisting of isopentane and 2,3-dimethylbutane, and also adding lof thereto an anti-knock agent.

2. The process of claim l in which the isobutylene alkylatingagent comprises monomeric isobutylene, and the n-butylene alkylating agent comprises monomeric butylene-i vand butylene-2.

3. The process of claim l in which the isobutylene alleviating' agent comprises di-isobutlyene, and the -nbutylene alkylating agent comprises -monomeric butylene-l and butylene-Z,

f i. The process of claim 1 in which the isobutylene alkylating -agent'comprises tri-isobutylene,

and the n-butylene alkylating agent comprises monomeric butylene-l and butylene-2.

mixture to the extent of 3-4 c c. of tetra-ethy i equivalent volatile blending fraction will usually be satisfactory for this purpose. Inlnbitors, al-

additional anti-knock agents, and

other iuel additives may be incorporated in these fuels in accordance with prior practices in this art. f

it is to be understood, of course, that the above examples are merely illustrative and donot limit the scope oi 'my invention. As has previously been pointed out, other methods may be used to separate isobutylene from the gais mixtures, and other procedures and combinations of reaction conditions may be employed for the hydrogen fluoride alwlation step and the sulfuric acid alkylation step. Likewise, diierent proportions,' or other equivalent components. may be used in the production of motor fuels from the alkylates produced by my process.. In general, it maybe said that the use of any equivalents or modications of procedure which would naturally occur to one skilled in the art is included in the scope of my invention. Only such limitations should be imposed on the scope of my invetian as are indicated in the appended claims.

c aim:

1. The process of manufacturing an aviation super-fuel which comprises alkylating isobutalne at-'a temperature oi dii-80 alkylating agent substantially free from iso.

butylene and selected from` the group consisting 'of butylene-l, butylene-2, secondary butyl 'alcohol and secondary butyl acid sulfate in the presence of strong H2804 of alkylation strength under conditions including a' feed ratio of iso-y butane, to n-butylene equivalent of the said .n-butylene alkylating'agent in excess of 5.5:1 and an internal ratiothereof in excess oi.' 100:1

monomeric isobutylene equivalent of the di-Jsoleast 5: 1, Arecovering a debutanized anti-.knock motor fuel -ing isobutane to the aikylatng agent selected from therefrom having a.

manufacture of a high which comprises subjectaction of an isobutylene the group consisting of isobutylene, di-isobutylene, tri-isobutylene, tertiary butyl alcohol and tertiary butyl uoride F. in the presence of a volume of substantially anhydrous hydrogen fluoride at least equal to the volume of hydrocarbons in contact therewith, while maintaining a molar ratio of isobutane to isobutylene alkylating agentof at least `5:31. basedon the monomeric isobutylene equivalent of said isobutylene alkylating agent.' recovering a debutaniaed alkylate clear CMM octane oci-"pat 5. A process forthe least es end subieeting imputan@ to the-action of an n-butylf'ene free from isobutylene and selected from the: group consisting of Toutylene-ll, 'butylene-Z, secondary `butyl alcohol and at a temperature of 95-60" secondary butyl acid sulfate F. in the presence of a volume of 94-190 per cent equal to the volume of hydrocarbons in contact therewith, while maintaining a molar ratio of iso- .butane to n-butylene alkylating agent o at least 5.5:1, recovering a. debutanized alkylate therefrom having a clear octane of at least 94, blending the said dbutanized alicylates,A and adding an anti-knock agent thereto.

6. The process of claim 5, butylene alkylating agent is monomeric isobutylene, and the n-butylene alkylating agent is a mixture of nonomeric butylene-li and butylene-2.

7. The process. of 4claim 5, in which the isobutylene alkylating agent is essentially di-isobutylene, and the n-butylene alkylating agent is a mixture of monomeric butylene-l and butylene-2.

Y 8. The process of claim 5, in which the isobutylene alkylating agent is essentially tri-isobutylene, and the n-butylene alkylating agent is a mixture of monomeric butylene-l vand butylene- 4 9. 'I h'e process of manufacturing an aviation super-fuel which comprises with di-isobutylene, in.- the tiallyanhydrous hydrogen iluorid'e under conditions including a molar ratio of isobutane. to

butylene or at valkylate therefrom having a clear CFRM octane of atleast about 95 and ctaining Iat least 35% by volume of of which more than sulfuric acid at least` in which the, iso-v alkylating isobutaneV presence of substanamidtins usent substantially A half is 2,2,4-trimethylpentane, separately alkylating isobutanoe with normal butylene substantially free from isobutylene in the presence of HzSO4 of 'at least 95% strength under tions including a feed ratio of isobutane to normal butylene in excess of 5.5:1 and an internal ratio thereof in excess of 100:1 with a space velocity below 1, recovering a debutanized alkylate therefrom having a clear CFRM octane of at least 94, blending the said alkylates, adding thereto about 5-20% by volume based on the blended alkylates of a hydrocarbon selected from the grouptconsisting of isopentane and 2,3-dimethylbutane, and also adding at least 3 cc. per gallon based on the resulting mixture of tetraethyl lead.

l0. A process for the production of isobutane to the action of an isobutylene alkylating agent'selected from the group. consisting of isobutylene, di-isobutylene, tri-isobutylene, tertiary butyl alcohol and tertiary butyl fluoride at a temperature of 60-80 F. in the presence of a volume of substantially anhydrous hydrogen fluoride at least equal to the volume of hydrocarbons in contact therewith, whilemaintaining a molar ratio of isobutane to isobutylene akylating agent of at least 5:1 based on the monomeric isobutylene equivalent 0f saidl isobutylene alkylating agent, subjecting isobutane to the action of an n-butylene alkylating agent substantially free from isobutylene and selected from the group consisting of butylene-l,

butylene-2, secondary butyl alcohol and secondary butyl acid sulfate at a temperature of` F. in the DIBSeIlCe 0f a Volume 0f condianti- Knock motor fuels, which comprises subjecting ene-isobutane hydrogen fluoride alkylate formed under conditions including a molar ratio of iso- `butane to, monomeric isobutylene equivalentof the diisobutylne in excess of 4:1, said alkylate having a clear CFRM octane of at least 95 and containing at least 85% by volume of octanes of which more than half is 2,2,4-trimethylpentane, blended with a substantial proportion of debutanized n-butylene-isobutane sulfuric acid alky-late formed under conditions including the substantial absence. of isobutylene and with a molar ratio of isobutane to n-butylene in excess of 5.5:l, said last-mentioned alkylate having a clear CFRM .octane of at least 94, together with about 5-20% by volume based on the volume of the blended alkylates of a light hydrocarbon selected from the group consisting of isopentane and 2,3-dimethylbutane, and at least 3 cc. per gallon based on the above mixture of tetraethyl lead.

l2. An aviation super-fuel comprising a substantial proportion of de butanized hydrogen iluoride catalyzed isobutane alkylate formed from an'isobutylene alkylating agent selected from the group consisting of isobutylene, diisobutylene, tri-isobutylene, tertiary butyl alcohol and tertiary butyl fluoride, under conditions including a molar ratio ofisobutane to mpnomeric isobutylene equivalent of the-isobutylene acid at least equal to fraction and tetraethyl -alkylating agent in isobutane. alkylate excess of 4:1, said debutanized alkylate having a clear CFRM octane of at least 95 and containing at least 85%, of oct/nes of which more'than half isv 2,2,4-trimethylpentane, blended with a substantial proportion of debutanized sulfuric acid catalyzed formed from a normal butylene alkylating agent substantially free from isobut'ylene and selected from the group consisting of butylene1,` butylene-Z, secondary butyl alcohol and secondary butyl acid sulfate, under conditions including a molar .ratio of isobutane to n-butylene equivalent of the said n-butylene alkylating agent in excess of 5.5: l, said last men- -tioned debutanized alkylate having a clear CFRM octane of at least 94, together with about 5-'20% .by volume based on the volume of the blended alkylates of a light hydrocarbon selected from the group consisting of isopentane and 2,3-dimethylbutane, and

an anti-knock agent. y 

